With a prior-art synthetic resin container, having a body part of substantially rectangular tubular shape, such as a biaxially-oriented, blow-molded bottle made of polyethylene terephthalate, the lower end of the rectangular tubular body part is closed with a bottom part that is curvingly depressed into the body part and a cylindrical mouth tube part is connected to the upper end of the body part via a shoulder part, which is continuous with the body part and has a truncated rectangular pyramidal tubular shape.
Also, a peripheral groove for reinforcing the buckling strength is provided along the periphery at a substantially central position in the height direction of the body part, the flat wall portions are provided with pressure reduction absorbing panels that deform in a depressed manner to absorb the pressure reduction that occurs inside a closed container, and the corner parts of the body part are corner wall parts with the edges removed.
Such synthetic resin containers having a body part of substantially rectangular tubular shape provide the advantage of hardly giving rise to any dead space when stored in cardboard boxes and handled for transport, etc., and thereby enabling efficient handling.
However, with the above-described prior art, when containers, containing contents in a sealed manner, are laid sideways and stacked on top of each other and a set of upper and lower containers are set in a state where the flat wall portion of the body part of one container abuts an edge-removed corner wall part of the other container, a portion extending from the body part to the corner part of the container, the flat wall portion of which is abutted against the corner wall part of the other container, deforms in a bending and depressed manner and this depression deformation increases and develops into permanent deformation with the elapse of time.
This invention has been made to resolve the above problem of the prior art and a technical theme thereof is to increase the resistance of the portion extending from the body part to the shoulder part of a rectangular tubular synthetic resin container against external forces from the sides, and an object of this invention is to enable stacked storage of such a type of synthetic resin container in a sideways-laid orientation, for example, stacked storage in a sideways-laid orientation in an automatic vending machine to be achieved and maintained safely.